1. Field of the Invention
The invention relates to a method of metallization in the fabrication of integrated circuits, and more particularly, to a method of forming an improved etch stop layer for metallization in the manufacture of integrated circuits.
2. Description of the Prior Art
In a common application for integrated circuit fabrication, a contact/via opening is etched through an insulating layer to an underlying conductive area to which electrical contact is to be made. A conducting layer material is deposited within the contact/via opening. The damascene and dual damascene processes have become a future trend in metallization. Trenches or vias and trenches are etched in an insulating layer. The trenches or vias and trenches are inlaid with metal to complete the contacts. In all of these processes, etch stop layers are required to accurately form the trenches and vias. Conventionally, a low pressure chemical vapor deposition (LPCVD) silicon oxynitride etch stop layer has been deposited using argon/helium as the carrier gas or a plasma-enhanced chemical vapor deposition (PECVD) silicon oxynitride etch stop layer has been deposited using helium as the carrier gas. There are a number of disadvantages to this conventional etch stop layer. Specifically, the uniformity across the wafer in terms of thickness, refractivity, and reflectivity of the oxynitride film is highly variable resulting in difficulty in etching and deposition.
U.S. Pat. No. 5,639,687 to Roman et al teaches forming a silicon-rich silicon nitride anti-reflective coating film using a LPCVD process. Oxynitride is not mentioned. U.S. Pat. No. 4,901,133 to Curran et al teaches forming a silicon-rich oxynitride film using a high temperature LPCVD process. U.S. Pat. No. 5,741,626 to Jain et al teaches a tantalum nitride etch stop and anti-reflective coating layer. U.S. Pat. No. 5,818,110 to Cronin shows a dual damascene process using a silicon nitride or silicon oxynitride etch stop layer. U.S. Pat. No. 5,578,523 to Fiordalice et al discloses a silicon nitride etch stop layer and an aluminum nitride polish stop layer deposited in the presence of helium or argon gas with no differentiation between the inert gases.